More than 2,200 bands turned virtually every square foot of the city into a music hall last year, and organizers promise to ramp it up even more in 2013.

Most of the acts that play won't leave Austin with a big contract. But it's worth noting that Alabama Shakes was considered SXSW's musical breakout last year, just months before the group won the Best New Artist Grammy.

Established artists will be hitting stages in Austin as well.

Green Day, the band that took snarly punk rock all the way to Broadway, will play one of this year's most anticipated sets. The performance will be their first major showcase since front man Billie Joe Armstrong checked himself into rehab seven months ago for what he called a drug- and alcohol relapse that culminated in a profanity-laced rant onstage in Las Vegas.

Dave Grohl has parlayed his drummer gig for one of the most influential rock bands of the last quarter-century (that's Nirvana, in case you forgot) into the front man role with perennial Grammy winner Foo Fighters and is now a sort of de facto spokesman for the world of rock.

He'll be the music keynote speaker for the festival.

Grohl will also be playing with his latest project, Sound City Players, which, against all logic, brings together artists ranging from Rick Springfield and Stevie Nicks to Creedence Clearwater Revival's John Fogerty to members of Slipknot, Fear and Rage Against the Machine.

Punk-rock icons Iggy & the Stooges will play, as will gothic troubadour Nick Cave, psych rockers The Flaming Lips and reunited British ska act The Specials.

Pop star/actor Justin Timberlake, who has become a bit of a tech entrepreneur in recent years, is hosting a private party and rumored to be pondering a surprise gig himself.